PONPC Question

Gordy

Well did it resolve the pressure issue?

I don’t know if I like what I see in the strainer

icy78

> @Gordy said:
> Well did it resolve the pressure issue?
>
> I don’t know if I like what I see in the strainer
I liked what i saw! It solved my problem. Probably not flushed well at install.

Yes it sure did solve the pressure issue. I couldnt believe when i climbed back up that id missed that strainer. Heck, i even hit my head on it🤯
Because of poor iso valve location i had to drain about 30 gallons of 30%.

So now at 28 supply side and 5 at the loop inlet. So still 52 53 fthd. MPV 2.5 from 90% open to 10% open was no change in flow, by the pump curve. Amp draw doesnt change either. Valve size was pipe size. Cv was 95 i think. Probably shouldve been a size smaller.?

Solid_Fuel_Man

53 feet of head seems like an awful lot for 300' of 1/2 pex and some 2.5" fittings.. I guess at around 2gpm per loop that's right, but why such high flow? Lumber warehouse with two doors isn't really anything too out of the ordinary.

icy78

> @Solid_Fuel_Man said:
> 53 feet of head seems like an awful lot for 300' of 1/2 pex and some 2.5" fittings.. I guess at around 2gpm per loop that's right, but why such high flow? Lumber warehouse with two doors isn't really anything too out of the ordinary.
>
>
>
>
>

Definatly not my forte here.! But very interesting. At 20 loops thats closer to 3+ gpm per. I thought that was high but i dont know enough about it. Whats usual design flow for infloor? Can anyone reccomend a good basic resource for me to start learning?
Eg factory literature, Uponor,....something better? Thanks!

Jamie Hall

6000 feet of half inch pipe? In a single loop? No. Sorry, just … no. Granted, that might account for the use of giant economy sized pumps, but that just doesn't add up. Now if those 300 foot loops -- still a bit on the long side -- are hooked up in parallel, that's a different story, although I would expect some wicked balancing problems between loops even if the manifold's were very carefully built and reverse return.

The pump diagram shows that the safe NPSH for those pumps is on the order of 10 psi at mid flow range, and up to 15 psi at full flow. To be safe, you need to have that 15 psi at the pump inlets; otherwise you will destroy them. The expansion tank or tanks should be close to the inlets (no more than a few feet of 1 inch minimum pipe, and no more than two bends. If there are isolation valves -- recommended -- they must be 1 inch full port ball valves, and never throttled), and precharged to 15 psi. The system pressure at that point should also be 15 psi.

It may have worked, after a fashion, but that's not an excuse for redoing it using much better design.

Gordy

There is 20 loops. 300’ each well with in range for 1/2” .

Jamie Hall

Gordy said:

There is 20 loops. 300’ each well with in range for 1/2” .

misread. Sorry

Gordy

If your pressure differential readings for the pumps are still accurate. You are pushing about 2.75 gpm through each loop. Provided of course everything is perfectly balanced, long shot.

Much we don’t know about the application. You mentioned snow melt, and it’s a lumber yard. Doors opening, and closing a lot ect. Design delta for the radiant we don’t know. Someone had a thought when designing this.

icy78

> @Gordy said:
> If your pressure differential readings for the pumps are still accurate. You are pushing about 2.75 gpm through each loop. Provided of course everything is perfectly balanced, long shot.
>
> Much we don’t know about the application. You mentioned snow melt, and it’s a lumber yard. Doors opening, and closing a lot ect. Design delta for the radiant we don’t know. Someone had a thought when designing this.

I asked. No one knows. I know how it goes at this company. Theres some design, but its haphazard.
It makes my job interesting because im constantly trying to learn so i can make what ever it is, work.
Theres no balancing valves. No reverse return. Theres snowmelt on a zone, such that when the snowmelt calls the lumberyard zone closes.
The piping work is usually pretty nice. In this case its Gruvlok. Neat and symmetrical . Alerton controls.
The problem is that one of our fitters will be told to run x size pipe for x pumps. He then pipes it as space permits and as he likes.
No one has training. Its still better than alot around hrre but its not as you would like it.
Dans books have shown me a lot and i try to bring that to my bosses but its tough. We do pump away now at least!

As far as design....say 30 btu/sqft so X gpm needed at 20 delta T , so tell Taco we need a pump to do this, and throw in an extank, now ,you go plumber!

As as n example, On the original prints i saw 40fthd . That would be around 90 gpm, at the far right of the curve. Ouch.

icy78

> @Jamie Hall said:
> 6000 feet of half inch pipe? In a single loop? No. Sorry, just … no. Granted, that might account for the use of giant economy sized pumps, but that just doesn't add up. Now if those 300 foot loops -- still a bit on the long side -- are hooked up in parallel, that's a different story, although I would expect some wicked balancing problems between loops even if the manifold's were very carefully built and reverse return.
>
> The pump diagram shows that the safe NPSH for those pumps is on the order of 10 psi at mid flow range, and up to 15 psi at full flow. To be safe, you need to have that 15 psi at the pump inlets; otherwise you will destroy them. The expansion tank or tanks should be close to the inlets (no more than a few feet of 1 inch minimum pipe, and no more than two bends. If there are isolation valves -- recommended -- they must be 1 inch full port ball valves, and never throttled), and precharged to 15 psi. The system pressure at that point should also be 15 psi.
>
> It may have worked, after a fashion, but that's not an excuse for redoing it using much better design.

I should look again but i thought the NPSH was about 10 feet. Not 10 psi.

Jamie Hall

You are right on the required NPSH. I'm very conservative with pumps, and I've never liked to run them that close to the specification, unless I am dealing with -- and know I will always be dealing with -- cold (50 F or less) water.

Zman

https://www.uponorpro.com/~/media/extranet/files/manuals/radiant/cdam 7th edition - full copy/cdam_manual_0611_webready.ashx?version=092520180417

icy78

> @Jamie Hall said:
> You are right on the required NPSH. I'm very conservative with pumps, and I've never liked to run them that close to the specification, unless I am dealing with -- and know I will always be dealing with -- cold (50 F or less) water.

Thanks Jaime. Pump suction is actually 7 psi now, so 16 fthd, so that's better.

Gordy

If you are only seeing 16' of head those pipes must be whistling dixie . No wonder those strainers where dirty. Everything's coming back, but the kitchen sink

icy78

> @Gordy said:
> If you are only seeing 16' of head those pipes must be whistling dixie . No wonder those strainers where dirty. Everything's coming back, but the kitchen sink

Hahaha! 🙂 No no, 16 feet on the suction side and 69ft on the supply. So still 53 total for 73 gpm.